Along with the wide use of mobile devices, communication services provided in real time, such as voice calls or streaming with mobile devices, have rapidly increased. Due to the rapid increase of communication services, the need for security of data transmitted and received also have increased.
In the related art, a protocol such as the Secure Real-time Transport Protocol (SRTP) is used to maintain security of data provided in real time. The SRTP is a type of Real-time Transport Protocol (RTP) and is intended to secure encryption, authentication, and integrity of data included in an RTP packet, which was developed and standardized by Cisco and Ericsson.
FIG. 1 shows an example of an SRTP packet format according to the related art.
Referring to FIG. 1, an SRTP packet includes an RTP header, a payload, an SRTP master key index (MKI), and an authentication tag. The RTP header includes version information, information about the presence or absence of a padding byte, a sequence number, a time stamp, and information about a payload type. The payload includes actually transmitted data such as video/audio data. The payload of the SRTP is encrypted.
The authentication tag is data for authenticating the integrity of an SRTP packet, and the SRTP MKI is index information indicating a master key to be used for decryption when a plurality of master keys are required to decrypt an SRTP packet. The SRTP MKI may not be included in a packet according to the implementation. The authentication tag and the SRTP MKI are data used to authenticate integrity of an SRTP packet or a payload included in the SRTP packet.
For the SRTP packet shown in FIG. 1, however, integrity check data such as the authentication tag and the SRTP MKI is added separately in order to authenticate data. Accordingly, the SRTP scheme has an overhead of 25.3% (that is, 21 bytes (data needed to authenticate integrity)/83 bytes (total packet size)*100) in comparison with the RTP scheme, thus wasting bandwidth.
Furthermore, there is an inconvenience that it is impossible to perform integrity authentication on a device that does not support the SRTP.